re: "I need to hire 200+ freelance recruiters for a 10-15 minute job. When I was creating the job posting, it says the maximum number of hires I can have is 99. What is the best way to do what I need?"

Just post the same job twice.

You can hire a bunch of people, and if you run out of hires... Create a new job posting based on the first job posting.

It sounds like you are on the Upwork Basic plan. On this plan, you will only be able to invite 3-freelancers to apply to your job. If your job post's visibility is public, freelancers will still be able to apply to your job post, regardless of your plan.

If you find the need to invite more freelancers to your job post, you may check these other available plans.